Polymorphic variation of the DEFB1 gene might contribute to the development of ankylosing spondylitis: a preliminary study.

BACKGROUND: Ankylosing spondylitis (AS) is an inflammatory disease that affects the spine and can cause peripheral arthritis, enthesitis, and dactylitis, as well as extra-articular manifestations such as uveitis and inflammatory bowel disease. ß-Defensins are antimicrobial peptides involved in the activation and regulation of several immune cell types that may influence the inflammatory response in AS. The aim was to analyze the association and interaction of two functional variants of the DEFB1 gene in AS patients, and their role with inflammatory markers. METHODS AND RESULTS: The rs11362 and rs1800972 variants were genotyped using TaqMan probes in Mexican AS patients and controls. C-reactive protein (CRP) levels and erythrocyte sedimentation rate (ESR) were quantified. SPSS software was used for statistical analysis and multifactor dimensionality reduction (MDR) for interactions. The AA and GG genotypes were associated with AS risk in the age- and sex-adjusted model (OR = 6.89, P = 0.008 and OR = 3.43, P = 0.046, respectively); furthermore, the A-G haplotype showed a significant association with AS risk (OR = 2.94, P = 0.012). ESR and CRP were elevated in carriers of the AA genotype compared to the GA and GG genotypes of the rs11362 variant (20.89 ± 9.78 vs. 5.63 ± 4.61 and 4.10 ± 2.65 mm/h, P < 0.0001; and 10.92 ± 14.09 vs. 2.14 ± 2.02 and 2.15 ± 2.13 mg/L, P < 0.001, respectively). Using the MDR method, strong interactions of the rs11362 variant with sex were identified in the adjusted and unadjusted models. CONCLUSIONS: These results suggest that the DEFB1 gene may play a key role in AS pathogenesis.

ß-defensin 1 Gene Polymorphisms are Associated with Kidney Disease in Northwestern Mexicans with Type 2 Diabetes.

Diabetic kidney disease (DKD) is one of the more limiting complications to the quality of life of diabetes mellitus patients. Studies including cultured cells, animal models, and case-control studies highlight the role of human ß-defensin-1 (hBD-1) in diabetes.This study assessed the association of hBD-1 gene (DEFB1) functional variations -52 G/A (rs1799946), -44 C/G (rs1800972) and -20 G/A (rs11362) with type 2 diabetes mellitus (T2DM) in order to investigate its effects on genetic susceptibility and progression to DKD in a Mexican population. A total of 214 T2DM patients with and without DKD (n = 102 and n = 112, respectively) and 117 healthy subjects participated in this case-control study. Genotyping was made by PCR-RFLPs. Clinical and biochemical parameters of all patients were measured. There was no statistically significant difference in genotype or allele frequencies between patients and healthy individuals. Nevertheless, compared with patients without DKD, DKD patients have a reduced prevalence of AA genotype of -52 G/A (OR = 0.307, 95% CI = 0.104-0.905, p =.026), as well as a higher frequency of GA genotype of -20 G/A variant (OR = 1.875, 95%CI = 1.031-3.409, p = .038). Our results suggest that rs1799946 and rs11362 could be useful variants to stratify T2DM Mexican patients in order to prescribe closer follow-up to prevent or retard DKD. Further tests in different ethnic groups are encouraged.

Association between genetic polymorphisms in the promoter region of the defensin beta 1 gene and persistent apical periodontitis.

AIM: To evaluate the association between the promoter region of defensin beta 1 (DEFB1) genetic polymorphisms and persistent apical periodontitis (PAP) in Brazilian patients. METHODOLOGY: Seventy-three patients with post-treatment PAP (PAP group) and 89 patients with root filled teeth with healed and healthy periradicular tissues (healed group) were included (all teeth had apical periodontitis lesions at the beginning of the treatment). Patients who had undergone at least 1 year of follow-up after root canal treatment were recalled, and their genomic DNA was extracted from saliva. Two single nucleotide polymorphisms (SNPs) in DEFB1 at the g. -52G>A (rs1799946) and g. -20G>A (rs11362) positions were analysed using real-time polymerase chain reaction. The chi-squared test was performed, and the odds ratios were calculated using Epi Info 3.5.2. Logistic regression analysis in the codominant model, using the time of follow-up as a variable, was used to evaluate the SNP-SNP interaction. All tests were performed with an established alpha of 0.05 (P = 0.05). RESULTS: For the rs11362 polymorphism in the codominant and recessive models, patients who carried two copies of the T allele had a significantly lower risk of developing PAP (P = 0.040 and P = 0.031, respectively). For the rs1799946 polymorphism in DEFB1 in the codominant and recessive models, carrying one copy of the T allele significantly increased the risk of developing PAP (P = 0.007 and P = 0.031, respectively). In the logistic regression, both polymorphisms were associated with PAP as well as the SNP-SNP interaction (P < 0.0001). CONCLUSIONS: Polymorphisms in DEFB1 genes were associated with the development of post-treatment persistent apical periodontitis.

Regulatory SNP rs5743417 impairs constitutive expression of human ß-defensin 1 and has high frequency in Africans and Afro-Americans.

The prediction of regulatory single nucleotide polymorphisms (rSNPs) in proximal promoters of disease-related genes could be a useful tool for personalized medicine in both patient stratification and customized therapy. Using our previously reported method of rSNPs prediction (currently a software called SNPClinic v.1.0) as well as with PredictSNP tool, we performed in silico prediction of regulatory SNPs in the antimicrobial peptide human ß-defensin 1 gene in three human cell lines from 1,000 Genomes Project (1kGP), namely A549 (epithelial cell line), HL-60 (neutrophils) and TH 1 (lymphocytes). These predictions were run in a proximal pseudo-promoter comprising all common alleles on each polymorphic site according to the 1,000 Genomes Project data (1kGP: ALL). Plasmid vectors containing either the major or the minor allele of a putative rSNP rs5743417 (categorized as regulatory by SNPClinic and confirmed by PredictSNP) and a non-rSNP negative control were transfected to lung A549 human epithelial cell line. We assessed functionality of rSNPs by qPCR using the Pfaffl method. In A549 cells, minor allele of the SNP rs5743417 G→A showed a significant reduction in gene expression, diminishing DEFB1 transcription by 33% when compared with the G major allele (p-value = .03). SNP rs5743417 minor allele has high frequency in Gambians (8%, 1kGP population: GWD) and Afro-Americans (3.3%, 1kGP population: ASW). This SNP alters three transcription factors binding sites (TFBSs) comprising SREBP2 (sterols and haematopoietic pathways), CREB1 (cAMP, insulin and TNF pathways) and JUND (apoptosis, senescence and stress pathways) in the proximal promoter of DEFB1. Further in silico analysis reveals that this SNP also overlaps with GS1-24F4.2, a lincRNA gene complementary to the X Kell blood group related 5 (XKR5) mRNA. The potential clinical impact of the altered constitutive expression of DEFB1 caused by rSNP rs5743417 in DEFB1-associated diseases as tuberculosis, COPD, asthma, cystic fibrosis and cancer in African and Afro-American populations deserves further research.

Human ß-defensin 1 update: Potential clinical applications of the restless warrior.

Human ß-defensin 1 (hBD-1) is a multifaceted antimicrobial peptide being a tumour suppressor and, depending on call of duty, capable of inducing self-nets and neutrophil extracellular traps (NETs) to capture and/or kill bacteria, participates in inflammatory responses in chronic diseases including hBD-3 upregulation and also capable of up/downregulation in the presence of certain species of Lactobacillus sp. Thus, is regulated by host microbiota. Alleles, genotypes and/or altered gene expression of its coding gene, DEFB1, have been associated with several human diseases/conditions ranging from metabolic/chronic (e.g. cancer), infectious (e.g. tuberculosis, HIV/AIDS), inflammatory (gastrointestinal diseases), male infertility and more recently, neurologic (e.g. depression and Alzheimer) and autoimmune diseases (e.g. vitiligo and systemic lupus erythematosus). The present update focuses on novel DEFB1/hBD-1 properties and biomarker features, its biological function and the pharmaceutical potential uses of antimicrobial peptide elicitors (APEs) or the engineered peptide in the treatment of hBD-1-related human diseases.

DEFB1 gene polymorphisms and tuberculosis in a Northeastern Brazilian population

Abstract β-Defensin-1, an antimicrobial peptide encoded by the DEFB1 gene, is known to play an important role in lung mucosal immunity. In our association study we analyzed three DEFB1 functional polymorphisms -52G>A (rs1799946), -44C>G (rs1800972) and -20G>A (rs11362) in 92 tuberculosis patients and 286 healthy controls, both from Northeast Brazil: no association was found between the studied DEFB1 polymorphisms and the disease. However we cannot exclude that this lack of association could be due to the low number of subjects analyzed, as suggested by the low statistical power achieved for the three analyzed SNPs (values between 0.16 and 0.50).

Prediction of the impact of coding missense and nonsense single nucleotide polymorphisms on HD5 and HBD1 antibacterial activity against Escherichia coli.

Defensins confer host defense against microorganisms and are important for human health. Single nucleotide polymorphisms (SNPs) in defensin gene-coding regions could lead to less active variants. Using SNP data available at the dbSNP database and frequency information from the 1000 Genomes Project, two DEFA5 (L26I and R13H) and eight DEFB1 (C35S, K31T, K33R, R29G, V06I, C12Y, Y28* and C05*) missense and nonsense SNPs that are located within mature regions of the coded defensins were retrieved. Such SNPs are rare and population restricted. In order to assess their antibacterial activity against Escherichia coli, two linear regression models were used from a previous work, which models the antibacterial activity as a function of solvation potential energy, using molecular dynamics data. Regarding only the antibacterial predictions, for HD5, no biological differences between wild-type and its variants were observed; while for HBD1, the results suggest that the R29G, K31T, Y28* and C05* variants could be less active than the wild-type one. The data here reported could lead to a substantial improvement in knowledge about the impact of missense SNPs in human defensins and their world distribution. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 633-644, 2016.

DEFB1 gene polymorphisms and tuberculosis in a Northeastern Brazilian population

Defensin-1, an antimicrobial peptide encoded by the DEFB1 gene, is known to play an important role in lung mucosal immunity. In our association study we analyzed three DEFB1 functional polymorphisms -52G>A (rs1799946), -44C>G (rs1800972) and -20G>A (rs11362) in 92 tuberculosis patients and 286 healthy controls, both from Northeast Brazil: no association was found between the studied DEFB1 polymorphisms and the disease. However we cannot exclude that this lack of association could be due to the low number of subjects analyzed, as suggested by the low statistical power achieved for the three analyzed SNPs (values between 0.16 and 0.50).(AU)

DEFB1 gene polymorphisms and tuberculosis in a Northeastern Brazilian population.

ß-Defensin-1, an antimicrobial peptide encoded by the DEFB1 gene, is known to play an important role in lung mucosal immunity. In our association study we analyzed three DEFB1 functional polymorphisms -52G>A (rs1799946), -44C>G (rs1800972) and -20G>A (rs11362) in 92 tuberculosis patients and 286 healthy controls, both from Northeast Brazil: no association was found between the studied DEFB1 polymorphisms and the disease. However we cannot exclude that this lack of association could be due to the low number of subjects analyzed, as suggested by the low statistical power achieved for the three analyzed SNPs (values between 0.16 and 0.50).

A Fast Method for DEFB1 - 44C/G SNP Genotyping in Brazilian Patients with Periodontitis.

AIM: Defensins are cationic antimicrobial peptides expressed in epithelial cells. Such peptides exhibit antibacterial, antifungal and antiviral properties, and are a component of the innate immune response. It has been suggested that they have a protective role in the oral cavity. This study evaluated the DEFB1 polymorphism in diabetic patients with or without periodontitis in comparison to healthy controls. MATERIAL AND METHODS: We used Hairpin-Shaped Primer (HP) assay to study the distribution of the -44 C/G SNP (rs1800972) in 119 human DNAs obtained from diabetic patients and healthy control patients. RESULTS: The results indicate that there are no differences in distribution between groups and that in diabetic periodontitis patients the homozygous mutant could be found more frequently. CONCLUSION: Further studies are necessary in order to investigate the role of DEFB1 polymorphisms in diabetic periodontitis patients and the influence of the peptide in periodontal pathogens.

Antimicrobial peptide elicitors: new hope for the post-antibiotic era.

Antimicrobial peptides or host defense peptides are fundamental components of human innate immunity. Recent and growing evidence suggests they have a role in a broad range of diseases, including cancer, allergies and susceptibility to infection, including HIV/AIDS. Antimicrobial peptide elicitors (APEs) are physical, biological or chemical agents that boost human antimicrobial peptide expression. The current knowledge of APEs and their potential use in the treatment of human infectious diseases are reviewed, and a classification system for APEs is proposed. The efficient use of APEs in clinical practice could mark the beginning of the urgently needed post-antibiotic era, but further trials assessing their efficacy and safety are required.